Physical Sciences and Mathematics Commons^™

The Weathering Of Platinum From Nuggets And Platinum Immobilisation By Cupriavidus Metallidurans, Sean Gordon Campbell

Electronic Thesis and Dissertation Repository

Two studies were conducted to investigate the biogeochemistry of platinum. In the first project, platinum nuggets were examined to evaluate mineral dissolution-precipitation processes occurring at the nugget-‘soil solution’ interface. The presence of dissolution ‘pits’, cavities, and striations as well as acicular, iron oxides coating the grain surface evidence that this interface is an important site of mechanical and chemical weathering. Element mapping revealed that structural and chemical signatures can be linked to morphological features on the grain surface. In the second study, the soil bacterium Cupriavidus metallidurans was reacted with aqueous platinum chloride and rapidly immobilised platinum. XANES/EXAFS analysis of …

Applicability Of The Eshelby Formalism To Viscous Power-Law Materials: A Numerical Validation, Zhenyu Zhong

Electronic Thesis and Dissertation Repository

Fabric is important for the interpretation of tectonic evolutions. In the process of extrapolating small-scale fabric to tectonics, modeling frameworks are needed. Neither the early kinematic models nor the contemporary computational geodynamics are able to capture the complexities of the fabric development in natural deformation systems. Eshelby proposed a formalism in micro-mechanics, and it is now well understood that this formalism works well for the linear viscous deformations. However, given that most of the natural rocks are power-law materials, the Eshelby Formalism cannot be directly applied to geological problems. This problem was largely solved when Lebensohn and Tom (1993, Acta …

An Investigation Of Deformation Structures And Their Tectonic Significance Across The Grenville Front Tectonic Zone In The Vicinity Of Sudbury, Ontario, Canada, Changcheng Li

Electronic Thesis and Dissertation Repository

The Grenville Front Tectonic Zone (GFTZ) is a polyphase deformation belt in the northwest of the Grenville Province which was shaped in the continent-continent-collision-induced Grenvillian Orogeny.

This thesis focuses on the evolution of deformation fabrics in the GFTZ between the Sudbury Basin and French River in Ontario, Canada. Geological mapping using a new digital mapping system was conducted within this segment of the GFTZ, in its northwest vicinity in the Southern Province, and in its southeast vicinity in the Grenville Province. The new digital mapping system includes a personal digital assistant equipped with an internal GPS and a mobile GIS …

Late Quaternary Histories Of Lakes Huron And Michigan: A Stable Isotope Investigation Of Sediment Cores And Modern Biogenic Carbonates, Rebecca A. Macdonald

Electronic Thesis and Dissertation Repository

Late Quaternary histories are investigated here for sediment cores from Lakes Huron and Michigan, using the oxygen- and carbon-isotope compositions of biogenic carbonates and the oxygen- and hydrogen-isotope compositions of porewater. Age models for these cores are based on sedimentological information, and where possible, radiocarbon and pollen dates. The Michigan Basin cores provide a thick record of the late Pleistocene, whereas the Huron Basin cores primarily record Holocene deposition. Taken together, the histories recorded in biogenic carbonates from these sediments provide a clear account of lakewater isotopic changes – and their significance – over much of the history of the …

Reconstructing Fire Severity From The Oxygen-Isotope Compositions Of Plant Char, Michael W. Hamilton

Electronic Thesis and Dissertation Repository

This study assessed whether variations in the oxygen-isotope compositions of char formed from biomass burning could be related to burning severity. Ground samples of oak (Quercus alba), pine (Pinus resinosa), and grass (Andropogon gerardii) were charred for 5 and 30 minutes at constant temperatures between 200 and 900°C under oxygenated versus anaerobic conditions. Char oxygen-isotope values became progressively depleted of ¹⁸O by up to 25.8‰ for wood and 16.5‰ for grass as temperature, duration of burning, and amount of oxygen increased. The primary reason for the decrease in oxygen-isotope values is the loss …

Studies Of Aftershock Sequences Of Large Subduction Zone Earthquakes, Armick Ivanian

Electronic Thesis and Dissertation Repository

Amongst the different types of earthquakes, it is observed that the mega-thrust earthquakes, which occur in subduction zones, are the most devastating. The aftershock sequences following the mega-thrust earthquakes can also increase the level of seismic hazard, even in remote areas away from the mainshock fault zone. This thesis examines the statistical parameters of aftershock sequences of large subduction zone earthquakes that have occurred in the western and eastern Pacific Ocean. These parameters are vital for seismic hazard assessment of regions located near subduction zones. The results show that, on average, the Gutenberg-Richter exponent—the b-value—is markedly higher in the …

A Geobiological Investigation Of The Mazon Creek Concretions Of Northeastern Illinois, Mechanisms Of Formation And Diagenesis, Andrea S. Fernandes

Electronic Thesis and Dissertation Repository

Siderite concretions from the mid-Pennsylvanian Francis Creek Shale of the Mazon Creek area, in northeastern Illinois, contain exceptionally preserved soft-tissue fossils. Scanning electron microscopy, energy dispersive spectroscopy, time of flight-secondary ion mass spectrometry and micro-x-ray diffraction on polychaete worm, jellyfish and holothurian samples highlighted detrital clay and quartz grains in siderite cement. The worm and jellyfish are pyritised and surrounded by pyrite halos, whereas the holothurian is preserved as a weathered impression. Specimens possessed either microbial textures or framboidal pyrite, in carbon-enriched zones. The carbon-enriched zones contained organic compounds, indicating that extensive degradation associated with high temperature diagenesis did not …

Relationships Between Earthquake Ground Motions And Modified Mercalli Intensity, Andrea Sweny

Electronic Thesis and Dissertation Repository

With widespread Internet use, web-based earthquake reports are a valuable source of felt intensitydata with broad geographical coverage. Paired with ground motion data, Internet surveys like theUSGS Did You Feel It? (DYFI) website can be used to derive relationships between ground motionparameters and Modified Mercalli Intensity (MMI). These are particularly important for regionswith sparse seismographic coverage where the quality and density of intensity data may be superiorto ground motion data. MMI-ground motion relationships are also needed to infer ground motionsof historical earthquakes.

Using well-documented earthquakes in across North America, we analyze correlations betweenfelt intensity and ground motions, including peak ground …

Thermal Plume Transport From Sand And Gravel Pits Potential Thermal Impacts On Cool-Water Streams, Jeffrey M. Markle

Electronic Thesis and Dissertation Repository

Potential thermal impacts from below-water-table aggregate extraction on a cool-water stream were investigated by monitoring thermal plumes, moving through an unconfined glacial-outwash aquifer, and assessing their subsurface persistence. The growing demand for aggregate and increased pressure to pursue extraction in ecologically sensitive areas has driven the need for this work. During a 10-year period, ground and surface water temperatures were measured monthly, including two periods of intensive monitoring (22 months and 2.5 years). The aquifer hydraulic conductivity (K) is quantified at the laboratory and field scale. The mean K’s from the multi-scale tests depend on test-support volume and …

Seismic Microzonation Of Great Toronto Area And Influence Of Building Resonances On Measured Soil Responses, Dimitar Genchev Mihaylov

Electronic Thesis and Dissertation Repository

A pilot seismic microzonation of the Greater Toronto Area (GTA) is used to establish the conditions and limitations of geophysical methods for site response investigations in city conditions. Maps of fundamental soil resonant frequencies, amplifications at these frequencies and interpolated average shear wave velocity of top 30 m of soil profile (VS- 30) used in soil classification were compared to the maps of drift thickness and surficial geology for the GTA. The non-applicability of the interpolated VS-30 map for site classification between measured test points is indicated. It is also shown that the soil response cannot be estimated properly using …

Ice-Movement History And Kimberlite Indicator Mineral Dispersal Study, Pelly Bay, Lower Boothia Peninsula, And Wager Plateau Areas, Nunavut, Canada, Carl Ozyer

Electronic Thesis and Dissertation Repository

This study reconstructs the ice flow history of the eastern portion of the Keewatin sector of the Laurentide Ice Sheet by integrating field work, remote imagery, and work by others. The study reveals at least seven ice flow phases during the Wisconsinan, including ice streams. A model was developed using inverse distance weighed (IDW) interpolation with GIS to identify and isolate potential kimberlite bedrock sources in kimberlite indicator mineral-rich areas in the Pelly Bay area, Nunavut. Kimberlite indicator mineral (KIM) data were normalized by “peer size” to better understand how KIM grains from three kimberlite sources are distributed within three …

Ergodicity And Seismicity Clustering With Applications In Statistical Seismology, Nelson Cho

Electronic Thesis and Dissertation Repository

The implications of understanding fault networks as ergodic systems are addressed here by using the Thirumalai-Mountain metric that identifies effective ergodic periods, when long but finite time intervals are considered. This framework was proven to be useful in statistical seismology studies. Initially, it was established that that the metric can be used to quantify seismicity clustering. Periods of effective ergodicity were characterized by the occurrence of declustered seismicity. This interpretation was implemented for synthetic and seismic data from southern California and Canadian mines.

Next, methods used in the estimation of regional seismic hazard were applied to mining induced seismicity. The …

The Complex Paragenetic History Of Basal Negaunee Iron Formation Iron Ores, Tilden Mine, Marquette District, Upper Michigan, Natalie J. Pietrzak

Electronic Thesis and Dissertation Repository

Variable mineral chemistry and textures of basal Negaunee iron ores mined in the Main Tilden Pit have led to metallurgical difficulties. Core-logging and detailed petrography supported by microprobe investigations, identify three upward fining lithofacies within the Main Pit Carbonate and overlying Martite ore domains: 1) Basal Clastics; 2) Medial BIF; and 3) Granular Iron Formation. Growth fault related subsidence controlled deposition of the Basal Clastics, comprised of detrital quartz dispersed in a matrix of chlorite, cemented by ferri-hydrite, chert and Mg-siderite. Subsequent starvation of any clastic input led to cyclic iron-silica precipitation throughout the deposition of Medial BIF. Increasing wave …

Coupled Heat And Water Transport In Frozen Soils, Ranjeet M. Nagare

Electronic Thesis and Dissertation Repository

The effect of freezing on soil temperature and water redistribution was examined in four Mesocosms maintained at different initial water content profiles. An innovative experimental setup involving use of a frozen base layer acting as a proxy to permafrost beneath an active layer made up of packed and undisturbed peat cores was used. The experimental setup was successfully validated for its ability to maintain one dimensional change in temperature and soil water content in frozen soil. There was a substantial amount of water redistribution towards the freezing front, enough to create an impermeable frozen, saturated zone within 15 cm of …

Uncertainty Estimation Of Extreme Precipitations Under Climate Change: A Non-Parametric Approach, Tarana A. Solaiman

Electronic Thesis and Dissertation Repository

Assessment of climate change impacts on hydrology at watershed scale incorporates (a) downscaling of global scale climatic variables into local scale hydrologic variables and (b) assessment of future hydrologic extremes. Atmosphere-Ocean Global Climate Models (AOGCM) are designed to simulate time series of future climate responses accounting for human induced green house gas emissions. The present study addresses the following limitations of climate change impact research: (i) limited availability of observed historical information; (ii) limited research on the detection of changes in hydrologic extremes; and (iii) coarse spatio-temporal resolution of AOGCMs for use at regional or local scale. Downscaled output from …

Late Pleistocene Climate And Proboscidean Paleoecology In North America: Insights From Stable Isotope Compositions Of Skeletal Remains, Jessica Z. Metcalfe

Electronic Thesis and Dissertation Repository

This thesis uses the carbon, nitrogen, and oxygen isotope compositions of mammoth (Mammuthus) and mastodon (Mammut) skeletal remains to reconstruct paleoclimate and paleoecology in Late Pleistocene North America. Analytical methods, sampling strategies, environmental adaptations and seasonal behaviors of proboscideans were investigated.

Reliable and reproducible results are crucial for a study of this nature. A persistent methodological problem in the isotope analysis of structural carbonate in bioapatite was solved by reacting bioapatite under “sealed vessel” conditions.

Growth rate determinations are critical for designing sampling strategies and interpreting results. Histological and isotopic measurements demonstrated variations in enamel growth …

Strategies For Waveform Tomography Of Long-Offset, 2-D Exploration Seismic Data, Andrew J. Brenders

Electronic Thesis and Dissertation Repository

Waveform Tomography, combines starting models from traveltime tomography with tomographic waveform inversion. This approach to inversion recovers a “best fit” velocity model by iteratively minimizing the misfit between the observed, frequency-domain waveform data and modelled, synthetic waveforms. The method is both computationally efficient and an improvement over ray-based tomographic methods. Synthetic benchmark studies and experiments with long-offset, 2-D, exploration seismic field data, demonstrate that Waveform Tomography can yield accurate, high resolution velocity models, vital in seismic exploration for hydrocarbons.

I first present an application of Waveform Tomography to long-offset, 2-D, synthetic marine seismic data using the 2004 BP velocity benchmark. …

Impact Of Geomagnetically Induced Currents On Power Transformers, Jonathan E. Berge

Electronic Thesis and Dissertation Repository

This thesis deals with the impact of Geomagnetically Induced Current (GIC) on power transformers in electrical power systems. A simulator to calculate the flows of GIC in an electrical power network, based on an assumed or measured induced geoelectric potential is proposed. This simulator includes all needed mapping techniques to handle a system that cover a large geographical area.

A correlation between GIC and the reactive power absorbed in the core of the saturated transformer is proposed. That correlation is used to estimate GIC in a transformer utilizing existing reactive power measuring infrastructure within the electrical grid without the need …

The Impact Of Climate And Transport On The Compositions And Textures Of Heavy Minerals In Modern Rivers Of New Zealand, Alexandre Aubin

Electronic Thesis and Dissertation Repository

The types, abundances and textures of heavy minerals in the 63-125 μm fraction of modern river sands were investigated in order to assess the controls of climate, tectonic setting, source composition, recycling, transport and diagenesis on the nature of sedimentary systems. Two rivers on the South Island of New Zealand were selected for detailed study; the Haast is a high-flow river located in the high precipitation region near the west coast, whereas the Ahuriri River has lower flow rates and is located in a drier region in the central South Island. In both river systems, the Zircon-Tourmaline-Rutile (ZTR) index increases …

The Holocene Paleolimnology Of Lake Superior, Ayumi Hyodo

Electronic Thesis and Dissertation Repository

This study describes contributions of glacial meltwater to Lake Superior over the last ~11,000 cal BP (calibrated years before 1950 AD). This research has been motivated by a desire to understand whether glacial meltwater discharge via the Great Lakes into the North Atlantic played a role in Holocene cooling events, such as the Younger Dryas. Rhythmites (interpreted as varves), lithological, mineralogical and grain-size variations, and radiocarbon dating were used to establish chronostratigraphic correlation among four sediment cores from Lake Superior (Duluth, Caribou and Ile Parisienne basins, Thunder Bay Trough). Glacial sediments were deposited between ~10,850 and ~8,800 cal BP. The …